The present invention relates to an EGR gas control system used of an internal combustion engine of diesel motor car, particularly to an electronic EGR gas control system.
A conventional electronic EGR gas control system known as prior art has been so constructed that a simple valve is provided in the EGR gas passage near the connection of suction pipe to the EGR gas passage and the valve is controlled to open and close by motor via a reduction gear as shown in Japanese Laid-open Patent Publication of International Application No. Hei 2002-521610).
A system known as another prior art has been so constructed that a curved pipe for letting in the EGR gas is provided in the suction passage in the downstream of a throttle valve, the curved pipe is made open towards the downstream of the suction passage and a valve is provided in the EGR gas passage connected to the suction pipe, and the valve is controlled to open and close by negative-pressure actuator as shown in Japanese Laid-open Patent Publication No. Hei 10-213019.